'Don't rely on science to stop biological clock'

Fertility doctors say there are no more people needing fertility treatment now than there were 10 years ago - it is just that people have become more anxious about having a family.

In this week's Scrubbing Up, Stuart Lavery, a consultant gynaecologist at Queen Charlotte's hospital and a director of the IVF Hammersmith fertility clinic, says, despite the wealth of new reproductive techniques every year, age is still the critical factor in whether they can achieve that dream.

Not a day seems to go by without a new advance in reproductive science and headlines reporting breakthroughs in fertility treatment.

These cold statistics hide an emotional rollercoaster of stress, anxiety and often enormous financial strain

Popular magazines display happy celebrities in their 40s presenting their new offspring to the cameras.

Fertility clinics are full of patients who have delayed starting a family and believe that assisted reproductive treatments such as IVF offer them a guaranteed insurance policy of becoming parents.

Cold hard statistics

Unfortunately, these expectations may not be realised, and a quick glance at the latest HFEA national data in the UK shows that only 24% of all IVF cycles resulted in a birth. This drops to 12% for women aged 40-42, and a heart breaking 3% for women age 43-44.

Biology displays a seemingly unfair asymmetry here: men are producing new sperm every second of their reproductive lives; whilst women are born with all the eggs they will ever have.

These cold statistics hide an emotional rollercoaster of stress, anxiety and often enormous financial strain.

They do, however, very effectively demonstrate the huge impact of female age on the chance of conceiving.

Biology displays a seemingly unfair asymmetry here: men are producing new sperm every second of their reproductive lives; whilst women are born with all the eggs they will ever have.

Recent research from the respected team at the University of Edinburgh has suggested that the time related decline in ovarian reserve of eggs might be even more rapid than originally thought.

Time critical

The study looked at 325 samples of ovarian tissue from females of all ages and constructed a mathematical model that could be applied at a population level.

The results were sobering: the average 30 year old woman will have just 12% of her original ovarian store of eggs, this drops to 3% at age forty.

There is strong evidence that women are delaying pregnancy compared to previous generations

Clinically we see this in the increased delays in conceiving as we get older: women aged 35 are half as fertile as those aged 31, at 38 fertility is halved again.

The biological clock also affects men, but less profoundly.

IVF is not an insurance policy

Only one third of 40 year old men impregnate their partners within six months of trying compared to men under 25.

This is partly due to an age related reduction in the quality of sperm production and partly to a decreased frequency of intercourse in older men.

There is strong evidence that women are delaying pregnancy compared to previous generations.

'Waiting for Mr Right'

The reasons are demographically complex and are frequently simplified somewhat unfairly in the media as 'women waiting for the next promotion or waiting to meet Mr Right.'

We need to be very careful that this sort of research is not used to scare women rather than help.

Many women continue to have babies into their 40s both naturally and with the help of fertility treatment.

It is however important that both men and women are supported in their reproductive choices, and a thorough knowledge of our biological clocks and the impact of age is critical in allowing fully informed decisions to be made about the 'right' time to start a family.

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